1. Field of the Invention
The present invention relates to solar technologies, and more particularly to solar concentrators.
2. Description of the Related Art
Space debris includes man-made non-functional objects that are either in Earth orbit or re-entering the atmosphere. Some examples of space debris include non-functional satellites and fragments from space vehicle explosions or collisions. Space debris is a hazard to future space vehicles because of the risk of collision.
Space debris can be separated into three categories by size: Category 1 (<1 cm); Category 2 (1-10 cm); Category 3 (>10 cm). In particular, there are about 100,000 to 10,000,000 pieces of Category 2 space debris within 1600 km of the Earth's surface. Thus, it is important to remediate the large population of Category 2 space debris to reduce the chance of collision.
High power lasers that either deployed on the ground or from space have been proposed as solutions to remediate Category 2 space debris objects. Earth-based lasers suffer huge propagation losses from atmospheric attenuation and turbulence, cloud obscuration, and pointing errors over the longer distances required to intercept debris. To compensate for the huge propagation losses, prohibitively high transmitter flux is required, making power requirements for ground lasers excessive and costly. The relatively low wall-plug efficiency of current laser technology makes space deployment very costly and virtually impractical relative to the launch costs, which place a severe limit on the size, weight and power (SWaP) of effective laser platforms.
Solar flux concentration has been proposed as a way to remediate Category 2 space debris. Solar flux concentration utilizes focused solar radiation to vaporize the space debris. In order to use solar flux concentration, a large area focusing system for concentrating sufficient solar radiation must be carried into space. Ordinarily, a typical focusing system has a lot of large and heavy optical components needed to enable high quality imaging, but solar flux concentration has less demanding requirements on surface curvature, especially using different technology (such as diffractive membrane optics), and the mass and bulk of conventional optical components make it impractical for spacecraft deployment of such large apertures.
What is needed for effective space debris remediation is a solar flux concentration system that that has a compact volume for easy transportation to space, yet provides a large surface area after deployment that is easily managed and directed.